1. Field of the Invention
This invention relates generally to production systems, and more particularly is directed to a production system suitable for use in producing an electronic product or device which can be controlled through an inner bus by an external computer or the like.
2. Description of the Prior Art
A production system has recently been proposed in which the production process is controlled by a computer in a concentrated or integrated control fashion. As a typical and well known example of such a production system, there is the so-called "just-in-time" inventory system developed in Japan and there referred to as the "Kanban" production system. According to this "just-in-time" inventory system, each product being conveyed along the production line bears a so-called kanban (sign board) in which work instructions or information and the like are written and, on the basis of such work instructions or information written in the sign board associated with each product, the assembly, adjusting and other necessary work are carried out by robots or manually.
In the field of electronic devices, such as, television receivers, VTRs (video tape recorders), audio tape recorders and so on, digital circuits are widely used. Most of these digitized devices employ an inner bus system. In such inner bus system, a CPU (central processing unit), an inner bus, a ROM (read-only memory) and so on are incorporated in the device, and predetermined or set values for operation of each circuit are stored in this ROM. Upon normal operation, the foregoing set values are read from the ROM by the CPU, and the data read out are supplied through the inner bus to a predetermined circuit, whereby such circuit is driven to carry out a predetermined operation. At the same time, each circuit is controlled through the CPU by an external instrumentality, such as, a keyboard, a remote controller and the like. The inner bus used in such inner bus system is usually a two-wire system bus or a three-wire system bus. The two-wire system bus is formed of a data transmission line and a clock transmission line, and may utilize a communication system such as is disclosed in published Japanese patent application unexamined No. 106262/1982. The three-wire system bus is formed of a data transmission line, a clock transmission line and a transmission line for an identifying signal which is used to identify a data block.
In the case of electronic devices equipped with the above mentioned inner bus system, the adjustment thereof during manufacturing and in use can be standardized, made common and simplified so that reduction of the manufacturing and other costs can be expected.
It is to be noted that, in the case of the prior art production systems, such as, the "just-in-time" inventory system, the indication of the work instructions or information and the like, impose a heavy load on a host computer. Further, since several manufacturing processes must be carried out simultaneously, the prior art production system requires a high-speed and large-sized computer.